Study On Heat Generation Model And Heat Dissipation Of Corrugated Cold Plate For Soft-Packed Lithium Battery

As a hot spot in the development of the new-generation automobile industry,electric vehicles have received great support and attention from countries all over the world in recent years.Especially in China,the emphasis on the development of electric vehicles is regarded as the road of technological innovation of “curving overtaking”.Therefore,as a power battery for electric vehicles,the thermal management problem is becoming more and more important.The thermal management performance will directly affect the power,cruising range,life and safety performance of electric vehicles.In recent years,due to the influence of power battery integration,liquid cooling is required to better meet the heat dissipation requirements of battery packs with greater power.To deal with the thermal characteristics of the power battery pack,first of all,it is necessary to study the heat production of the lithium battery,and secondly,it needs a proper cooling mode to analyze whether the heat dissipation effect of the battery pack is reasonable.This article uses LG's soft-pack lithium battery as the basic research object,its main work is as follows:(1)Explain the structure and working principle of the soft-pack lithium battery,and determine the core heat generation model based on Bernadi's heat production formula,and use a constant heat source for the positive and negative ear;and explain the transmission under different cooling modes according to the theory of heat transfer.Thermal mechanism.Finally,the basic theory of CFD mathematical model is expounded.(2)Using the experimental equipment,build a charging and discharging test rig,determine the experimental scheme,record the voltage,capacitance and other changes with time under different ambient temperature and discharge rate,and verify the influence coefficient of the ambient temperature on the electromotive force temperature through data collation.Neglect,and then study the variation law of the electromotive force temperature influence coefficient with SOC;in addition,it also includes the ohmic internal resistance of the soft-packed lithium battery,the polarization internal resistance with the ambient temperature and SOC,and the single cell at different ambient temperatures and different discharge rates.The temperature change curve of each measuring point.(3)Simplify the structure of the battery cell,and use the CATIA software to establish the geometric model of the battery cell based on the geometric measurement data.The pre-processing software ANSA divides the grid,and refers to related data and calculation methods to determine the physical parameters of the battery core and the ear portion.The response surface model was used to determine the thermal model based on Bernadi based on the experimental analysis data.The dynamic thermal characteristics of the battery cells at different discharge rates and different ambient temperatures were simulated and compared with the temperature rise data of the experimental tests.The accuracy of the thermal model.(4)By changing the cold plate structure of the corrugated small channel,20 cold plate models with different wave heights and different corrugation angles are established,and the original DC small channel cold plate and the existing corrugated cold are completed by numerical analysis method of computational fluid dynamics.The analysis of the flow and heat transfer performance of the plate is based on the combination of pressure loss and heat transfer performance.The model with a wave height of 1 mm and a waviness angle of 140 degrees is the preferred corrugated channel cold plate structure.(5)Based on the previous three chapters,the factors affecting the heat dissipation performance of the corrugated small channel cold plate battery pack were studied,including the material difference of the thermal conductive sheet,the inlet temperature of the coolant,the inlet speed,and the ambient temperature.It is concluded that the higher the thermal conductivity of the thermal conductive sheet,the lower the temperature of the battery pack,the better the heat transfer performance,but the greater the temperature difference of the single battery;the higher the inlet temperature of the cooling liquid,the worse the cooling of the battery pack,the average of the monomer The higher the temperature,the lower the temperature difference;the higher the inlet speed of the coolant,the lower the temperature of the battery pack,but the temperature difference of the monomer gradually increases;the higher the ambient temperature,the higher the temperature of the battery pack.